Herd immunity: Protecting vulnerable members of the community

Herd immunity: Protecting vulnerable members of the community

Do you live in an area where a lot of people are protected against a specific virus? If you do, your community may have ‘herd immunity’.

Herd immunity is when a community as a whole is protected from a contagious disease because many of the people who live there each have protection from it(1) and, therefore, cannot pass the infection onto others. Unable to pass from one person to the next, the virus finds it difficult to spread.

How herd immunity works

A virus spreads when one infected person infects other people they come into contact with; then those people infect others that they come into contact with(2).

Imagine living in a community where protection against a specific virus is low. Someone becomes ill. Most of the people they encounter are not protected. They pass the virus on with ease(3). The disease spreads quickly through the community.

Now imagine living in a community where protection against a specific virus is high. Someone becomes ill. Most of the people they encounter are protected. The virus is unable to spread(3). The disease disappears quickly, keeping the whole community well.

Why is herd immunity important?

With herd immunity, well-protected people are also helping to protect vulnerable members of the community(4); the elderly, the very young, pregnant women and people living with chronic diseases(4), in particular.

Their lack of protection may be for one of several reasons. It may be because they are unable to get vaccinated for medical reasons(2). Or it may be because a vaccine does not work well for them(4), for instance.

Herd immunity and vaccination

Vaccination protects individuals directly and communities indirectly by reducing transmission(5). However, herd immunity does not give us as individuals the same high level of protection as vaccination(3). Avoiding vaccination and just relying on indirect protection through herd immunity is, therefore, not a good alternative to getting a flu shot.

For the flu, research has shown that at least 70% of people in a community need to get an annual flu shot for herd immunity to be reached(2). Have you had yours?


References
(1) https://www.ovg.ox.ac.uk/news/herd-immunity-how-does-it-work
(2) https://www.reuters.com/article/us-health-vaccines-education/explaining-herd-immunity-may-convince-more-people-to-get-flu-shots-idUSKBN1JW2MC
(3) https://vk.ovg.ox.ac.uk/vk/herd-immunity
(4) https://www.tandfonline.com/doi/full/10.3109/00365548.2011.582247
(5) https://www.sciencedirect.com/science/article/pii/S0264410X18306571

Comments

Leave a comment